U is a subspace of the set of all polynomials P, it contains all polynomials of the form p=az^2+bz^2. Find the subspace W of P st P = U+W

U+W is the span of P, not sure how to represent it.

I meant to make a new thread.

Are you sure about "p= az^2+ bz^2"? That is no different from "all polynomials of the form p= az^2".
(And is not a subspace- it does not contain the 0 "vector". You probably meant "all polynomials of the form p= az^2+ bz+ c".)